In the fabrication of complimentary metal oxide semiconductor (CMOS) integrated circuit devices with metal gates, deposition methods for the gate metals which include thermal evaporation (from Knudsen cells) and chemical vapor deposition are preferable since they lead to minimal gate dielectric damage and minimal long-term reliability problems. Other physical vapor deposition processes such as sputtering and e-beam evaporation lead to gate dielectric damage which is thought to be a long-term reliability problem even if some damage may be repaired by a forming gas or by a hydrogen anneal treatment. In general, chemical vapor deposition has the advantage over thermal evaporation in that it can be used to fill higher aspect ratio damascene features allowing for a wider variety of metal gate integration schemes.
While the deposition of Re metal by using a chemical vapor deposition technique has been attempted by others in the art, the deposited Re films using a halide precursor causes problems of halogen incorporation and high growth temperatures. Other attempts to grow Re films by using Re2(CO)10, as a precursor resulted in films with high carbon concentrations.
Despite the potential use of rhenium carbonyl in semiconductor applications, there is no disclosure of using Re2(CO)10 as the CVD source material for providing p-channel Re gates on dielectric materials such as ultra-thin (i.e. <50 Å) gate dielectric materials.
It is therefore an object of the present invention to provide a method for fabricating a metal oxide semiconductor (MOS) device with Re gate electrodes that do not have the drawbacks or shortcomings of the conventional methods.
It is another object of the present invention to provide a method for fabricating a metal oxide semiconductor device with gate electrodes fabricated from a metal selected from Re, Rh, Pt, Ir and Ru.
It is a further object of the present invention to provide a method for fabricating a field effect transistor encompassing gate electrodes fabricated of Re, Rh, Ir, Pt or Ru that has a work function compatible with pFET requirements.
It is another further object of the present invention to provide a field effect transistor equipped with gate electrodes formed of a metal that can withstand high hydrogen pressures necessary for producing proper passivated interfaces without undergoing chemical changes.
It is still another object of the present invention to provide a method for fabricating a field effect transistor equipped with gate electrodes that are compatible with post processing temperatures of up to 1000° C.